Progress in understanding and treating Parkinson's disease depends upon adequate animal models. The centralized production and maintenance of animals for the various projects will allow direct correlation and comparison of the results on morphological, biochemical, pharmacological, and molecular manipulations described in this program project application. The primary function of the Animal Core is to generate animals with striatal DA depletions, including rats with 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal system and mice treated with the neurotoxin N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), for use in the Projects. In addition, the Core will provide 6-OHDA-lesioned rats injected with retrograde tracers. The Core does the surgeries and drug treatments and is extensively involved in the overseeing the quality of the treatments. The animals produced and maintained by the Core will be accessed extensively by all four Projects, and provide the cornerstone of the studies that are proposed.